Domain: Eukarya
Eukarya is the domain that arose 1.7 billion years ago from prokaryotic organisms. It includes all organisms that contain membrane-bound organelles, such as mitochondria. This is unlike the other two domains, Bacteria and Archaea, where cells do not have membrane bound organelles. Eukarya includes fungi and protists, such as Plasmodium falciparum and the Shiitake Mushroom.

Kingdom: Animalia            
Members of the kingdom Animalia represent a wide array of organisms that exhibit qualities such as: being eukaryotic, heterotrophic, multicellular, motile at some stage in their life, and lack cell walls. These organisms can range from being as small as a tick to as big as a blue whale(to learn about other types of whales, you may want to consider visiting these pages about the Beluga whale or the Orca whale.) Sicarius hahni falls under this kingdom and demonstrates all of these characteristics, evident by how it eats insects, is multicellular, motile, and lacks cell walls.

Phylum: Arthropoda            
All spiders fall in the phylum Arthropoda, which is by far the most successful of any phyla falling under the kingdom Animalia. This is because the class Hexapoda (insects) is represented in this phylum, which accounts for over half of the species diversity on the planet! Spiders are in this phylum because of their chitinous exoskeleton, segmented bodies, and paired-jointed appendages. Some other great examples of arthropods are the Summer Fishfly, alderfly, and crane fly.

Class: Arachnida            
This class represents organisms such as mites, ticks, scorpions, and spiders. Arachnids were some of the first arthropods to move into a terrestrial environment. This class also lacks antennae, mandibles, and the body is split into two distinct regions: the cephalothorax and abdomen. They also have a pair of pedipalps, which are another pair of appendages not used for walking.

Order: Araneae            
This classification includes only the spiders. Spiders may be one of the most recognizable orders of invertebrates because of their ability to produce silk from their abdominal glands. They range in size from about 0.5 mm to 20 centimeters in length, have four pairs of legs, four or less pairs of eyes, two distinct body regions, fangs, and a pair of palps used for mating. Some other organisms falling under this classification are the Sydney Funnel-Web Spider and the zebra spider.

Family: Sicariidae            
This family of spiders is divided into two genera: Loxosceles and Sicarius. There are about 123 species in this family, which was first proposed in 1991 by Platnick, based on synapomorphies in spinneret morphology and a similar venom toxin.  

Genus: Sicarius            
Sicarius refers to the genus of spiders commonly called the six-eyed sand spider. The English translation of the word is “assassin” or “hit man.” This is no surprise, given the way the spider buries itself under the sand and secretly attacks its prey.

Species: Sicarius hahni            
As was just mentioned, the genus name Sicarius is Latin for “assassin” or “murderer.” The species name Sicarius hahni, is named after the founder of this spider, arachnologist Carl William Hahn. The common name, six-eyed sand spider, got its name because of the spider’s distinct ability to camouflage itself with sand, along with having three pairs of eyes. The common name can refer to the specific Sicarius hahni species, but can also refer to any of the species under the genus Sicarius.

Phylogenetic tree of classes Arachnida and Arthropoda Photo Credit: Dessie Underwood

This is a phylogenetic tree outlining the evolutionary relationship between members of the class Arachnida and other classes under the phylum Arthropoda. Every group seen on the tree is part of the class Arachnida except for the top three. Sicarius falls under the Araneae classification, the fourth from the bottom. This tree was created by Wheeler and Hayashi in 1998 based on 93 morphological characters, 1000 bases of 18S rDNA, and 350 bases of 28S rDNA.







G.J. Binford et al. / Molecular Phylogenetics and Evolution 49 (2008) 538–553

This phylogenetic tree represents the divergences of species under the family Sicariidae. As mentioned before, the two genus in this family are Sicarius and Loxosceles. This tree was constructed using 28S rDNA, and the nodes labeled A through E show the timetable of when some of the divergences of genus and species happened. The divergence of the Sicarius species happened 130-157 million years ago and based on some of the other nodes labeled, Sicarius hahni must have first appeared from 27-98 million years ago.


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